FIG. 1 illustrates a concept of a cellular wireless communication system.
A number of Base Stations (BSs) are configured so as to cover an entire region of a specific wireless communication system and each BS is configured so as to provide a specific wireless communication service to User Equipments (UEs) in a corresponding region. All BSs may provide the same communication service and may also provide different communication services. Recent multi-cell wireless communication systems are designed to allow a number of adjacent BSs to communicate with a UE using the same frequency band.
FIG. 2 illustrates a concept of a wireless communication system using multiple sectors in an independent cell.
As described above with reference to FIG. 1, each BS generally provides a communication service to a corresponding geographical region which can be divided into a plurality of smaller regions Cell 1, Cell 2, and Cell 3 in order to improve system performance. Each of the smaller regions may be referred to as a cell, a sector, or a segment. Signal interference may not only occur between cells belonging to different BSs as shown in FIG. 1 but may also occur between cells belonging to the same BS as shown in FIG. 2.
The overall performance of the wireless communication system may be reduced if the influence of interference caused by adjacent cells is not taken into consideration in the multi-cell system. For example, referring to FIG. 2, if a specific UE is located between BS1 and BS2, signals that the BS1 and BS2 transmit to the specific UE using the same frequency band affect the specific UE at similar strengths. A downlink signal of the BS1 and a downlink signal of the BS2 cause interference to each other. If a communication system is configured without taking into consideration the influence of such interference, there is a problem in that it is not possible to optimize system throughput since channel state information (also referred to as channel quality information) that the UE feeds back to the BS is incorrect.
As a result, in order to optimize throughput of such a communication system, it is important to configure a communication system so as to allow the UE to correctly measure a channel state between an adjacent cell and the UE and/or to correctly measure a channel state of a serving cell taking into consideration the level of interference caused by adjacent cells.